Assessment and comparison of microcirculation and macrocirculation in horses undergoing emergency exploratory celiotomy versus elective surgical procedures.

OBJECTIVE: To assess oral buccal microcirculation by hand-held videomicroscopy in horses during colic surgery, comparing microcirculation values with macrocirculatory parameters and with those of healthy elective surgical horses. STUDY DESIGN: Clinical prospective study. ANIMALS: Client-owned horses (nine in the colic group; 11 in the elective group). METHODS: In the colic group, buccal mucosal side stream dark-field microscopy (DFM) videos, cardiac output (CO), mean arterial pressure (MAP), and lactate were obtained at three timepoints under general anesthesia (30, 90, and 150 min after induction). Video analysis was used to determine total vessel density, proportion of perfused vessels, perfused vessel density, and heterogeneity index. Dark-field microscopy videos, MAP, and lactate were obtained at a single timepoint under general anesthesia (45 min after induction) in the elective group. RESULTS: There were no differences in microcirculatory parameters between colic and elective horses, nor was there a difference across timepoints in the colic group. There was a weak negative correlation between microvascular parameters and CO (rho = -0.23). CONCLUSION: The colic group did not have decreased microcirculation in comparison with the healthy elective group. Dark-field microscopy did not correlate well with macrocirculatory parameters in the colic group. IMPACT: Dark-field microscopy may not be a sensitive enough indicator to detect differences in microcirculation between colic and elective groups. The lack of difference in microcirculation may be due to sample size, probe location, or variation in disease severity.

Prevalence of intra-abdominal hypertension in horses with colic.

OBJECTIVE: To determine an abdominal pressure cutoff value for intra-abdominal hypertension (IAH) in the horse and characterize IAH in horses with acute colic. DESIGN: Prospective clinical cohort. SETTING: University teaching hospital. ANIMALS: Nine healthy adult horses and 56 horses with acute colic. INTERVENTIONS: Ventral intra-abdominal pressure (IAP) was measured in triplicate at end expiration and averaged. Each colic case was classified as medical or surgical and large intestine (LI) or small intestine (SI). Management and final outcome (alive, euthanized, or died) were recorded. IAH was defined as ≥32 mm Hg (mean + 2 SDs of ventral IAP in control horses). Proportions of horses with and without IAH for different lesions were expressed as fractions and percentages. Differences in IAP between groups were determined using ANOVA with post-testing or t-tests. Odds ratio for management strategy (ie, need for medical or surgical) in horses with IAH was performed using Fisher's exact test. P < 0.05 was considered significant. MEASUREMENTS AND MAIN RESULTS: IAP was higher in horses with colic compared to controls (P = 0.025). Over 18 months, 30.4% of horses with colic had IAH (n = 10 LI lesions, n = 7 SI lesions). Horses with LI medical lesions had the highest IAP of all lesions (mean 36.5 mm Hg). IAH horses with medical lesions were 15 times more likely to survive than IAH horses requiring surgery (P = 0.03). CONCLUSIONS: Acute colic in horses is associated with an increased ventral IAP compared with healthy controls. IAH does exist in horses with colic, notably LI medical lesions, and is associated with nonsurvival in horses that require surgery.